Abstract:
The generation of excessive levels of spicy aroma and the airborne dust in spice
grinding mills is one of the main ergonomic problems of the workers and sometimes
create social problems due to environmental pollution. Although the fine dust as well
as the aromatic chemicals has an economic value, collection of them is fairly a
difficult task under small-scale processing plants. A technically and economically
feasible low-cost dust filtration system was designed to filter and maintain the
concentration of airborne dust level below the recommended level of 10 mg/m3
for 8-
hour exposure time, in a spice grinding plant. The dust filtration system was designed
based on a similar principle as in the existing spry tower filter. However, the method
does not require very high pressure for fluid atomization as in that system and the
unit can be fabricated using locally available materials with a very high lifetime.
Dust measurements were carried out using a special cloth bag-collecting device with
a fixed airflow rate. Dust removal rates were determined with different
concentrations of a foaming shampoo (Lifebuoy shampoo) and a non-foaming
detergent (‘Rinso’ automatic washing machine powder). Results showed that the
filtration unit is capable of filtering airborne dust with an efficiency of 91% with the
foaming detergent while an efficiency of 78% with the non-foaming detergent. An
initial dust load of 108-150mg/m3
in the air was reduced to 9.6mg/m3 with the
foaming detergent and 32mg/m3 with the non-foaming detergent or tap water without
any detergent. Therefore, the dust filtration system is effective only with the foaming
detergent. The cost of the system is about Rs.11000.00 (US $ 110) and the estimated
additional cost for dust filtration per one kg of processed chilli powder is about 52
Cents (US $ 0.005).
